There are different types of microphones, some of which are designed to pick sound equally from all directions, while some are designed for picking sound from some particular directions. Polar patterns help in determining the sensitivity of microphones towards sounds that arrive from different directions.

The polar pattern helps in determining the area around the microphone where the pick up is excellent. For the output of the audio to be of high quality, the sound source must be placed within this area. The sound out of this pattern, although picked by the microphone, will be of a lower quality of audio.

Depending on the polar pattern or the direction of pickup, the polar patterns are classified as omnidirectional, unidirectional and bidirectional polar patterns. The microphones are designed by using various principles to achieve the desired polar pattern.

The omnidirectional polar pattern is also known as non-directional polar pattern. In this polar pattern, the sound is picked from all the directions i.e. from 360 degrees. This polar pattern produces uniform frequency response to frequencies of all ranges and from all directions.

The microphones which have omnidirectional polar pattern allow sound from all directions and hence, are not good at blocking the unwanted sound. The microphones with this type of polar pattern are especially good for live performances and for recording the crowd noises since they produce a very natural sound.

Microphones with unidirectional polar patterns can pick up sound from one particular direction rejecting all the other sounds. These microphones must be aimed in the direction where the sound source is. This type of polar pattern rejects the sound that is produced at the sides or rears and hence produces output with desired sound only. This feature makes it best suitable for use in television broadcasting.

The polar pattern produced in bidirectional polar patterns is of shape ’8′ which is why they are also referee to as figure-8 patterns. The microphones with bidirectional polar patterns pick up the sound from two directions, namely the front and the rear. These microphones reject the sound from the sides. The natural sound that the bidirectional microphones produce makes them suitable for use as studios and broadcast microphones.

Cardioid polar pattern is one of the most common unidirectional polar patterns. Cardioid microphones are so called this because the polar patterns produced by these are heart shaped. Cardioid microphones pick up sound from within 120 degrees of the direction in which they are faced. The Cardioid pattern helps in recording the sound that is directly in front of the microphone and produces a rich and high quality sound.

A combination of an omnidirectional and a bidirectional microphone is what makes the cardioid microphone. At the back, there is a negative signal of the bidirectional microphone and a positive signal of the omnidirectional microphone. They both cancel each other. At the front there are positive signals from both and hence add up.

A Stereo pattern is the combination of two patterns typically cardioid. In this pattern, two microphones are integrated into one single unit. This type of unit is used for broadcasting or field recording.

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